Question

Structure of a human sperm is shown in the figure with labels A and B. Identify these and give their characteristics.

• A. A : Plasma membrane - Envelope whole sperm
  
• B. A : Acrosome - Its enzymes helps in fertilisation
  
• C. B : Mitochondria - Provides energy for fusion of sperm with ovum
  
• D. B : Polysomes - Synthesise enzymes to facilitate fertilisation

Answer 1

The correct option is B A : Acrosome - Its enzymes helps in fertilisation


Spermatozoa
Spermatozoa is a functional male gamete containing 23 chromosomes.
It possesses acrosome, head, neck, middle piece and tail.

Label ‘A’
Label ‘A’ is acrosome.
Acrosome is a structure present on the head of the sperm derived from golgi bodies. It contains enzymes called sperm lysins. Sperm lysins in acrosomes dissolve egg envelopes and facilitate fertilisation.

Label ‘B’
Label ‘B’ is the mitochondria.
The middle piece has multiple mitochondria arranged spirally around the axonema (the central strand of flagellum). Mitochondria provide energy for the motility of sperm.

Polysomes
Polysomes are ribosomes bound to the mRNA. They are mainly found in the mitochondria of the sperms. It synthesises the proteins and enzymes required for fertilisation.

Plasma membrane
Plasma membrane is the outer protective covering of sperm.

Labelled sperm
Pictorial representation of the labelled sperm: